IM open opinion champion has the best shoes

Not pacing the flow of the information about his speech.

Explanation:

In any case of public speaking, there are certain methods that a person can utilize to ensure that the audience knows and understand what's been talked about. Moreover, certain tips like the pace/flow of the speech, the words used, the expression, the delivery, etc. all help in making a successful public speech/talk.

In the given scenario, Kelly knows he has a good hold of British royal history. And that he can deliver any talk or speech on that topic as much as people want. But when he began with the lineage of Queen Elizabeth, his audience seemed already so bored with the historical facts mentioned or presented. This shows that Kelly missed pacing the flow of the information he's sharing about the history of the royal family. He loves and knows the history well, but he should also consider his target audience and try to move along with how they can best understand his speech.